Expansion-bit



(No Model) G. NICHOLS.

EXPANSION BIT. N0. 289,126. Patented Nov. 27, 1883.

N4 PETERS. Hula-MW wm'ngm. 11C.

UNITED STATES PATENT OFF CE.

GEORGE NICHOLS, OF SEYMOUR, CONNECTICUT.

EXPANSION-BIT.

' SPECIFICATION forming part of Letters Patent No. 289,126, dated November 27, 1883.

Application filed September 24, 1883; (K0 model.)

To all wjwm it may concern:

Be it known that I, GEORGE NicHoLs, of Seymour, in the county of New Haven and State of Connecticut, have invented a new Improvement in Expansion -.Bits; and I do hereby declare the following, when taken in connection with accompanying drawings and the letters of reference marked thereon, to be a full, clear, and exact description of the same,

and which said drawings constitute part of this specification, and represent, in

Figure 1, a front view; Fig. 2, side view; Fig.3, diagram, enlarged to illustrate the ad justment of the cutter.

This invention relates to an improvement in that class of wood-boring implements which are designed to be adjusted so as to bore holes of different diameters, commonly called expansionbits, and particularly to that class of bits in which an opening is made diamet: rically through the head, and through which the cutter-bar is passed and clamped. Usually the opening through the head "has been made angular shape, to correspond to the like angularshape of the cutter-bar, and so that the cutter har would be forced into one of the angles by means of a set-screw in the head.

To make an angulanshaped hole through the head to receive the bar is an expensive operati'on and requires special tools for doing it.

The object of my invention is to cheapen this construction of bit; and it consists in a round hole bored diametrically through the head, combined with a cutter-bar having its back rounded corresponding to the round surface of the hole, and a setscrew in the head to bear upon the opposite side of the cutter-bar and force it to its place, as more fully hereinafter described;

A represents the head provided with the screw-point B, in the usual manner. Diamet- 'rically through the head above the screw or center cutter I bore a round hole, a, of a size to admit the cutter-bar. The cutter-bar D is made with its back rounded, corresponding to the surface of the hole in the head, and into the head in front of the cutter-bar a set-screw, d, is introduced to bear against the front surface of the cutter-bar and force it against the rear surface of the hole, as seen in Fig. 2. The

front surface of the cutter-baris made concave, as shown, and the lower edge sharp, so as to form the cutter. The bar is provided at its outer end with the spur e, as in other cutter-bars. By this construction I am enabled to make the hole or seat for the cutterbar in the cheapest possible manner-that is to say, simply drilling a round hole diamet rica-lly through the head. The fitting of the bar to this hole is very simple, as it may be struck in dies of the required shape; then it will only be necessary to polish the surfaces. Thus I avoid the expensive fitting of the cutter bar to the head when made of the usual angular shape. Again, the angular-shaped hole through the head positively locates the cutter, so that it cannot be adjusted with relation to the cutting-edge. By making the hole round and the back or boring portion of the cutter corresponding to the inner surface of that hole I am enabled to turn the cutter axially, as indicated in Fig. 3, to different cutting positions, a desirable advantage, for the reason that for different kinds of wood it is desirable to change the pitch of the cutter in order that smooth boring may be accomplished. Therefore, while cheapening the construction of the bit,

I improve it for general uses.

I am aware of Patent No. 22,195, and claim nothing therein shown or described.

I claim The herein-described expansioubit, consist ingof the head A, constructed with the point B, and with adiametrical round hole through the head, combined with the cutter-bar having its front side flattened and its lower side beveled to form a cutting-edge along the under side of the bar, the back of the bar rounded corresponding to the inner surface of the diametrical hole through the head, and with a set-screw in the head at right angles to the axis of the head and to the bar, and so as to bear upon the front flattened side of the bar and above the cutting edge, and force its back against the surface of the round hole in the head, substantially as described.

GEORGE NICHOLS.

Witnesses:

MAR-IA L. PARKER, S. HART OULvER. 

